GHSA-FWVG-7877-39CM
Vulnerability from github – Published: 2025-05-16 15:31 – Updated: 2025-11-17 18:30
VLAI
Details
In the Linux kernel, the following vulnerability has been resolved:
net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc
As described in Gerrard's report [1], we have a UAF case when an hfsc class has a netem child qdisc. The crux of the issue is that hfsc is assuming that checking for cl->qdisc->q.qlen == 0 guarantees that it hasn't inserted the class in the vttree or eltree (which is not true for the netem duplicate case).
This patch checks the n_active class variable to make sure that the code won't insert the class in the vttree or eltree twice, catering for the reentrant case.
[1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/
Severity
7.8 (High)
{
"affected": [],
"aliases": [
"CVE-2025-37890"
],
"database_specific": {
"cwe_ids": [
"CWE-416"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-05-16T13:15:52Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc\n\nAs described in Gerrard\u0027s report [1], we have a UAF case when an hfsc class\nhas a netem child qdisc. The crux of the issue is that hfsc is assuming\nthat checking for cl-\u003eqdisc-\u003eq.qlen == 0 guarantees that it hasn\u0027t inserted\nthe class in the vttree or eltree (which is not true for the netem\nduplicate case).\n\nThis patch checks the n_active class variable to make sure that the code\nwon\u0027t insert the class in the vttree or eltree twice, catering for the\nreentrant case.\n\n[1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/",
"id": "GHSA-fwvg-7877-39cm",
"modified": "2025-11-17T18:30:22Z",
"published": "2025-05-16T15:31:02Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-37890"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/141d34391abbb315d68556b7c67ad97885407547"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/273bbcfa53541cde38b2003ad88a59b770306421"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2e7093c7a8aba5d4f8809f271488e5babe75e202"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6082a87af4c52f58150d40dec1716011d871ac21"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8df7d37d626430035b413b97cee18396b3450bef"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ac39fd4a757584d78ed062d4f6fd913f83bd98b5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e0cf8ee23e1915431f262a7b2dee0c7a7d699af0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e3e949a39a91d1f829a4890e7dfe9417ac72e4d0"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
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- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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